There are two variants of the backpack, and both can be obtained from the gear crate. There is a brown backpack with a camo pattern, as well as a green backpack with no camo, but with a bedroll on top. The brown camo and the green backpack have the same icon but are two different looking cosmetics when applied on the avatar. This item was only sold one time in the Trail Blazer set and can no longer be purchased.
Backpack
Camo backpack
Green backpack
Backpack applied on the default outfit
Camo backpack applied on the default outfit
Green backpack applied on the default outfit